The systems denominated “auxiliary cold start up”, generally known by the technique, include a gasoline reservoir with an electropump injection, which, through an electrovalve and of a “one way (unidirectional) valve, provides the injection of a certain amount of gasoline inside of the intake manifold or in an area close to the intake valve of the cylinder, in the moment of the engine start up and during the accelerations in the engine warm up period. The amount of gasoline and the feeding time are commanded by the electronic unit that acts directly on the electropump injection, through a relay, as well as on the electrovalve.
However, and in spite of the extensive application of these systems in alcohol vehicles, which are not free from inconveniences. Specifically, the amount of gasoline injected gasoline is critical on several points of view, and among them one can point out its direct influence together with the emission of pollutants by the vehicle. On the other hand, the injection of an insufficient amount of gasoline does not allow the start up of the engine, damaging and reducing the useful life of the starter engine and providing an evident dissatisfaction of the user.
It also is related to the control of the amount of injected gasoline the driveability during the warm up period of the engine, the strong influence in the levels of pollutant emissions and in the fuel consumption.
Another negative factor of the cold start up systems that use the gasoline is the clogging of the inlet pipe and of the calibrated hole through where the gasoline is injected. This occurs mainly due to the gasoline aging that remains for a long time inside of the reservoir without being used, therefore the gasoline oxidizes, loses properties and it incurs on the gum formation. This happens because the start up of this system only occurs on colder days of winter, where, for the operation of the cold engine, the presence of the gasoline is necessary. Examples of this technology are shown in Brazilian Patent Applications Pl 8801648-0 and Pl 9002905-4
Moreover, the distance between the inserting of gasoline point, located in the intake manifold, and the intake valves cause an undesirable accumulation of gasoline on the walls of the intake manifold, causing losses to the cold start up system. Such problem is even more serious when dealing with engines with intake manifold of long branches. In order to solve this problem, a Brazilian Patent Application Pl 0300761-8 was recently proposed, which consists of an injection auxiliary system, endowed with auxiliary outlet of fuel injection for cold start up, and the injection being made closer to its burning point.
For startup optimization, driveability during engine warm up and subsequent decrease of the pollutant emission levels, a cold start up system was developed for cold alcohol engines that use an injection nozzle (5th nozzle) to introduce the gasoline in the intake manifold. For intake manifolds of long branches, the system uses two injector nozzles (one for each two cylinders) positioned close to the intake valve and close the entrance of the cylinder, according to Brazilian patent applications Pl 9905212-1 (5th nozzle) and C1 99052121 (with two additional nozzles) of this same depositor.
The inserting of gasoline in the intake manifold through injector nozzles allows a better control on the amount and form of gasoline injection, in the moment of the cold start up and during the warm up period of the engine. This gasoline control in an optimized way is not possible with the conventional system, in other words, the inserting of gasoline in the intake manifold through a pipe with calibrated hole.
The system described in Pl 0300761-8 refers to the inserting of auxiliary fuel (gasoline or vapors coming from the fuel tank) for cold start up through an adjacent channel to the fuel injector nozzle, this way the auxiliary fuel can be added close to the intake valve and together with the main fuel. This request presents a great similarity with the objective of the system described in C1 99052121 process, where the two additional injectors close to the intake valves pulverize the gasoline to aid the start up and cold operation of the alcohol engine. In order to substitute the auxiliary gasoline injection, several systems were proposed, and these contemplate the alcohol warm up and consequently the elimination of the gasoline and of every necessary apparatus for the constitution of an auxiliary system of cold start up, which can present flaws and provide problems for the operation of the engine. In the system described in the Brazilian patent application MU-7502050-5, the necessary time for the complete alcohol warm up can be very long due to the need to warm up before the oil that involves a coil to obtain of a desirable temperature of the alcohol contained in the coil.
US 2007/0056570 (ELIA et al, 2004) describes a system where the alcohol is warmed up inside the nozzles injectors, the amount of fuel warmed up can be insufficient for the cold accelerations, because the largest flow of necessary fuel in this operation at low temperatures cannot be promptly warmed up inside the small volume that is inside the nozzle injector.
In the system where the warmed up alcohol is inserted in the intake manifold, a loss of heat can occur inside the ducts and the fuel can get to an insufficient temperature in the combustion chamber. In order to reduce this possibility, U.S. Pat. No. 5,894,832 to Nogi et al teaches the fuel heating inside the fuel injector. The fuel injector is connected to a tubular idle air mixer chamber surrounded by electrical heaters through which a partial quantity of intake air is taken during the engine idle. Downstream this structure, the warmed up air/fuel mixture is addressed to engine cylinders through ducts. However, this system is just directed to idle engine operation (throttle valve closed), that means, it is limited and focused to cold start up and to engine warming up in idle engine operation. To higher intake air conditions (higher rotational speed—RPM), Nogi's proposed system is not able to fulfill the proper and sufficient heating of air/fuel mixture once the air intake flux through intake duct is much higher than the allowable air flux by Nogi's heating system. When a driver needs to quickly move the vehicle after its cold start up, Nogi's system will not work properly and engine will collapse (turn off). Reminding that the flashpoint (temperature from which there can be enough amount of fuel vapor for the combustion) of the alcohol is 13° C. and its combustion below this temperature is difficult, in situations of engine operation under very low temperatures such systems can become ineffective, because besides the loss of heat, a considerable amount of alcohol can remain deposited on the ducts walls (condensation).
This way a new cold start up system for alcohol engines or with the possibility to use in multi-fuel engines (flex engines) constitutes the object of the present invention, which allows the elimination of all necessary apparatus for the gasoline injection, as aid in start up and the cold acceleration.
This new system substitutes the conventional system of inserting of gasoline during the cold start up and engine warm up period, by an air warm up and/or alcohol system. Depending on the environment temperature the air intake and the alcohol warm up can be made separately. Otherwise, it is possible the air/fuel mixture temperature and warm up to be effectively reached and kept even in higher rotational speed operational condition, other than in idle operational condition. According to present invention, this operational characteristic is reached due to the combination of electrical heaters and working method, as described below.
The air intake warm up is made by electric heaters positioned strategically on the parts that compose the intake system, in other words, in the suction pipe and/or air filter and/or body of the throttle and/or collector conduits and/or headstock conduits or in each one of these parts separately, or combining these possibilities.
The warmed up air can also be supplied by an electric powered turbine, which has electric resistance (or heater) systems for the air warm up and the circulation forced into the intake manifold.
Considering only the main injectors (one for each cylinder), the alcohol warm up can be made by resistances positioned in the entrance of each injector and/or inside each injector and/or by a resistance for every nozzle holder pipe. For the alcohol warm up one can combine these three positions of the resistances or in each of these points separately.
Another form for the alcohol warm up is the use of one or two additional injector nozzles (supplementary) for the inserting of warmed up alcohol in the intake manifold. In this condition, the alcohol warm up may or may not exist in the main injectors or in the main holder of nozzles. In such case, the alcohol warm up through the use of the supplementary injectors can be made in a similar way, in other words, for resistances positioned in the entrance of each supplementary injector and/or inside of each supplementary injector and/or by a resistance for every supplementary pipe holder of nozzles. For the alcohol warm up in this condition one can combine these three positions of the resistances or in each one of these points separately. This system with alcohol warmed up supplementary injectors is interconnected to the main system, in other words, the work pressure is the same for all injectors. As the inserting of warmed up alcohol in the intake manifold is made through injectors, the same condensation possibility or deposit on the walls is minimized, therefore the alcohol mass contained in the “spray” is almost driven in its totality inside the cylinders.
This concept of use of supplementary injectors is the same one that this applicant described in Brazilian patent applications Pl 9905212-1 (5th nozzle) and C1 99052121 (with two additional nozzles). The great advantage of the use of the supplementary injectors is that the warm alcohol output can be controlled and adjusted (via ECU) as in the main injectors.